After Super Tuesday, we can no longer avoid asking the following question: What would Donald Trump’s foreign policy be, if he had one?

The word “policy” implies a whole range of cognitive acts — research, reflection, discussion — that are alien to this creature of impulse, hunch, and spontaneous combustion. Trump no more has policies than a shark has plans. He does, however, have intuitions about the world, views drawn out from the stamping, shouting crowd and then re-appropriated as his own. A Trump policy represents a point of conjunction between man and mob.

Trump thinks — and perhaps Trump thinks his listeners think — that the world wants to eat our lunch. That’s why the central metaphor of his world view is The Wall, whether literally in the case of stopping Mexicans or figuratively in the case of Middle Eastern refugees or trade with China. In the schlock-regal press conference he delivered from the gilded Mar-a-Lago ballroom after his Super Tuesday victory, Trump blustered that China, Japan, and Iran had all gotten the best of weak-willed American negotiators. As president, he vowed, he would show those countries who was boss. What’s more, he declared, “We’re going to make the military bigger and better and stronger than ever before, and nobody — nobody — nobody — is going to mess with us, folks. Nobody.”

Got that? Nobody — that’s America’s goal. There may be allies out there, but Trump rarely bothers with them. Foreign countries want what we’ve got, and they’ll get it unless we hit them harder than they hit us. The word for this view is not quite isolationism; it’s nationalism. Internationalists think that America shares collective interests with other countries and thus profits from working closely with them. Nationalists think defensively; the home front, for them, is always jeopardized. So Charles Lindbergh thought, and Patrick Buchanan. Of course, they were also isolationists. The wall — coastal defense, homeland security, embargos, tariffs — is the emblem of isolationism.

Trump is hardly the only nationalist/isolationist in the running. Sen. Ted Cruz wants to bar the door to Muslim immigrants and “carpet-bomb” the Islamic State; the only foreign leaders he seems to feel warmly towards are Middle East autocrats like Egypt’s Abdel Fattah al-Sisi. Bernie Sanders, meanwhile, is a nationalist of the left. Sanders very much admires some countries, especially the northern European welfare states, and wishes the United States would be more like them. It’s American power he doesn’t believe in. Asked in a recent debate how he would keep America safe from terrorist attack, he attacked Hillary Clinton for favoring “regime change” and reminded his listeners that, in 1953, Iran’s democratically elected prime minister, Mohammad Mossadegh, was “overthrown by British and American interests because he threatened oil interests of the British.”

It’s instructive that Trump and Sanders are the only candidates who have lit a fire under the American people. They understand that a very large fraction of the American electorate doesn’t think the United States can do much of anything to shape a better world, and views foreign affairs as a drain on national resources and a waste of time. In his desperate tag-team assault on Trump with Mitt Romney, Sen. John McCain warned voters of choosing a man demonstrably ignorant of the world. Yet Lindsay Graham, who wears McCain’s colors on foreign affairs, made zero impact on GOP voters. Sen. Marco Rubio, another McCainiac, has made a bigger dent, but not with his activist foreign policy.

I don’t think Donald Trump will become president — though I recognize that my confidence on that score bears some resemblance to the Angeleno’s faith that his city won’t be leveled by an earthquake. But even supposing that Hillary Clinton wins, the deep nationalist vein that Trump and others have mined makes one wonder how she’ll be able to conduct the activist, internationalist foreign policy she advocates.

President Barack Obama, who as a candidate spoke of the imperative to help shore up weak and failing states, has repeatedly had to promise an impatient American public that he will do his nation-building at home rather than abroad. If he drew down forces too deeply in both Iraq and Afghanistan, he did so in part because he knew the public wanted out. Drones, yes; soldiers, no. A President Hillary Clinton might face an even surlier mood than Obama has.

I don’t think foreign policy elites have fully absorbed this collective attitude. The Atlantic Council and the Brookings Institution has just published a report on the Middle East that concludes that the United States must engage much more forcefully in in the region if it is to prevent a catastrophe already in progress. The authors conclude that Washington must dispatch significantly more troops to Iraq than the 3,300 now there; train and equip a rebel force in Syria powerful enough to bring the Assad regime to the negotiating table; get Europe to take the lead on Libya; persuade the Saudis to stop trying to pummel the Houthis into submission in Yemen, and make Arab allies see the wisdom of sweeping political and security-sector reform.

On balance, I’m more skeptical than the authors are about the ability of the United States to promote liberal values and decent governance in the Middle East; nevertheless, as the report notes, the obvious alternative is strategic withdrawal from the region, and that’s far worse. The authors are, however, positively blithe on the question of domestic public opinion. “Numerous polls,” they note in passing, “show a strong majority in favor of doing more and committing more resources … to deal with the problems of the Middle East.” If those polls are right, President Obama has seriously misread the mood of the American people. So have Donald Trump and Bernie Sanders.

I think what those polls measure is the willingness to bomb the hell out of the Islamic State. But if a future President Clinton argued, as the Brookings authors do, that the United States, in concert with others, should substantially increase its assistance to Arab and North African states, she would quickly discover the limit of that alleged commitment. Yet America should do so; nurturing development is strategically, economically and morally preferable to building walls. What’s more, President Obama has already tried the experiment of leaving Iraq, Afghanistan, and Libya more or less on their own in order to foster self-reliance; it didn’t work, and his successor will inherit the consequences.

Leadership, of course, means persuading citizens to go where they would rather not. A President Clinton would have to find the language to convince Americans that a deep and ongoing engagement with the world, even a very intransigent and ugly world, is in the national interest. President Obama, for all his rhetorical gifts, never made the sale, and I’m skeptical that the plodding and prosaic Mrs. Clinton will do better. The only advantage she might have is that Trump’s candidacy could so damage Republicans further down the ticket that Democrats might regain control of the Senate, and thus eliminate one very large obstruction to her plans.

The gap between what the United States needs to do abroad and what voters would like it to do has rarely been larger. The only consolation is that no national mood lasts forever. More widespread economic growth (if it ever returns) might break the nationalist fever. Something positive might happen in the world — say, the abrupt demise of the Islamic State. Hillary Clinton, should she become commander-in-chief, just might discover in herself the grit and the gifts needed to persuade Americans that their diplomatic, economic and, yes, military power can be a force for good. Until then, the new president, like this one, will be sailing in very stiff winds.